1. Field of the Invention
The present invention relates to a weld joint between two rails arranged behind each other along a rail track.
2. The Prior Art
The invention relates to a weld joint between two longitudinally adjoining and aligned rail sections, each rail section having a rail foot, a rail stem and a rail head forming a running surface, the adjoining rail sections having facing ends defining a gap therebetween and the weld joint connecting the facing ends of the adjoining rail sections.
Various methods are already known for the joining of facing ends of immediately successive rail sections of a rail used in railway or tramway tracks, for example. If such joint weldings are made in laid tracks, the so called aluminothermic welding process is often used. During aluminothermic welding metal powder is melted and in its liquid state poured into a mould which surrounds the rail ends so that, like in a kind of casting process, the gap is filled between the opposite faces of the facing ends of the rail sections which face each other, thus ensuring a good connection between them.
Another welding method used is the flash-butt welding process, which is used to weld rails in laid tracks but is particularly useful for the production of weld joints in rail warehouses. This method keeps the abutting surfaces during current passage in such slight contact that the material burns away continuously at the small local contact points due to high current density. The liquid metal is then ejected from the abutting point. When the consumption zone is deep enough, welding is done by abrupt upsetting and simultaneous interruption of circuit. The liquid material which was squeezed out of the rail gap causes the development of a burr at the weld. This burr is removed by shearing and subsequent grinding.
Moreover, in track systems having a high level of rail load and wear, particularly in curves, it is customary to rebuild the rail head section through resurface welding. For this purpose open or submerged arc welding or shielded arc welding is often used to deposit filler material onto the rails, especially in the region of the rail head flanks. The material which juts out is then removed by grinding, thus producing the required shape of the rail head.